Optofluidic Nanoplasmonic Biosensors for Next Generation Point-of-care Immunoassays Abstract: Building predictive models of immunity requires comprehensive understanding of the complex and dynamic functional behavior of immune system. A need for such understanding is obvious with a number of immune related diseases for which viable treatments are not currently available. Cytokines are well-studied proteins secreted by immune cells and essential for intercellular signaling to regulate the maturation, growth, and responsiveness of particular cell populations. Previous studies suggest that quantification of cytokine-based immune fingerprints provides clinically and immunologically useful information related to infectious diseases, cancer, autoimmune diseases, and allergy transplantation. The ongoing revolution in fundamental biology, immunology and clinical discovery critically hinges on the availability of diagnostic tools capable of decentralized point-of-care measurements to provide immediate quantitative information of cytokine levels at the bedside or in the clinic. Current existing clinical technology is mainly based on Enzyme-linked immunosorbent assay (ELISA). The complex labelling and washing processes require a total assay time up to more than a few hours and a sample volume of 0.1- 2 mL per test per patient, which greatly hinders its application for immune monitoring at the point of care. Thus, there is an emerging clinical demand for transformative platforms that can perform multi- parametric cytokine detection to understand the dynamical immune response of the patient in a rapid and accurate manner. This requires collecting time series data that could be on the order of seconds for ion transport, to hours for changes in protein levels, and to days for phenotypic changes in host body with sensor sensitivity from biological relevant concentration to single molecular level using minimum sample volume. To address this need, the central objectives of this MIRA application are to develop integrated optofluidic nanoplasmonic biosensing platforms for rapid, high throughput, sensitive and multiplex cytokine detection from whole blood to single-cell level towards next-generation point-of-care immunoassays. The PI proposes the following three projects: 1) Label free, ultra-sensitive, high throughput nanoplasmonic serum immunoassay for real-time immune monitoring; 2) Multi-parametric cellular functional immunophenotyping assay for personalized immunomodulatory therapy; 3) Nanoplasmon ruler for direct visualization of single-cell cytokine secretion and cell-to-cell communication. The planned multi-scale research both experimentally and theoretically will bridge the gap in fundamental understanding of immune system and enhance the applicability, diagnosis and prediction power for immune system diseases. The proposed platforms would ultimately gear the biologists and clinicians with capability to real-time monitor the immune status in patients, a transformative achievement that has enormous implications to fundamental research and clinical applications.